Out-of-print for over 125 years, the original McGuffey's Eclectic Readers are considered educational classics. You can download it free at Gutenberg or McGuffey's Online Tutor.
McGuffey Primer for Grades pre-K, K-1
This book begins with the alphabet, moves to simple one-syllable words in object lessons.
Click on the links to McGuffey's Eclectic Primer Lessons and to all the resources we have made so far at McGuffey's Online Tutor.